Prior art devices of the type disclosed have a complicated design and construction which has a severe effect on the possibility of utilising the device in modern contexts which have high requirements of versatility and, above, all rapidity. A further drawback resides in the fact that prior art constructions require extensive maintenance and, as a result, lengthy down times.
The tasks forming the basis of the present invention are to provide an improved device and to obviate or at least reduce the above-outlined drawbacks.